This invention relates to the preparation of N-chlorocarbonyl isocyanide dichloride via the chlorination of methyl isocyanate and/or methyl carbamic acid chloride.
It is known that .alpha.-halogen isocyanates can be obtained by chlorinating isocyanates or their HCl-adducts, namely carbamic acid chlorides (German Offenlegungsschrift No. 1,122,058). It is also known that, in the case of perchlorinated methyl isocyanate, it is only the chlorotropic form, namely N-chlorocarbonyl isocyanide dichloride, which is present (Angewandte Chemie, Vol. 74, page 849 (1962)), although the known process for producing N-chlorocarbonyl isocyanide dichloride is not suitable for working on a commercial scale on account of the low yields obtained.